This invention relates generally to the field of valves and more particularly to a valve which can be installed on a fluid line while the line remains in service to carry fluid.
Fresh water is typically distributed in buildings through copper or plastic tubing. In order to install a valve on a water line which is already in place, it is necessary to first close a valve which is located upstream from the area of the pipe to which the new valve is to be applied. The pipe must then be drained, and a section must be cut away to provide room for installation of the new valve. The free ends of the pipe are fitted in the opposite ends of the valve body and are soldered, glued, solvent welded or otherwise secured and sealed to the pipe. In the case of copper pipe, soldering is normally used, while solvent welding is used for plastic pipe. Screw threads, bell couplings, flanged connections, and other techniques are also used at times.
In all cases, it is necessary for the water supply to be cut off and for the pipe to be drained. As a consequence, water service must be removed from the pipe and all of the appliances and facilities it serves. The water service must remain off until installation of the valve has been completed, and this can take a considerable amount of time and can result in considerable inconvenience to the building occupants. Installation of the valve also requires a skilled worker who must shut off the water supply, drain the water line, cut the correct section of the pipe away, install the valve in the removed section of the pipe, solder or solvent weld the valve body to the pipe, and then turn the water back on again once the valve has been installed. The skills required ordinarily are those of a trained and experienced plumber.
Another problem is that a valves on water pipes and other fluid lines can remain open for extended periods of time, thus exposing the valve seats to minerals in the water or other fluids. Calcium and other deposits can build up on the seats to such an extent that they do not permit the valve to seat properly when closed. Consequently, the valve leaks as a result of mineral build-up on the valve seats.
In refrigeration systems and other fluid systems which contain relatively expensive fluids, component replacement often requires complete draining of the system which can result in loss of expensive fluid. For example, when a refrigeration compressor is to be replaced, the refrigerant must be drained before the old compressor is removed, and the system must be charged with new refrigerant after installation of the new compressor has been completed. In view of the increasing lost of refrigerant, the need to recharge the system can result in significant expense.